A bearing ring for a roller bearing includes a raceway for at least one roller that includes an at least partially spherically formed roller end surface having a first curvature. A flange for transferring axial forces extends from an end of the raceway and has a flange surface that faces towards the roller end surface. A spherical flange surface section having a second curvature is defined on the flange surface. The first curvature differs from the second curvature such that a first gap (d1) exists between the spherically formed roller end surface and the spherical flange surface section. The flange surface also includes an opening flange surface section having a third curvature, which is less than the second curvature, such that a second gap (d2) exists between the roller end side and the opening flange surface section. The second gap is larger than the first gap.
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10. A roller bearing comprising:
at least one roller having an at least partially spherical roller end surface with a first curvature, and
a bearing ring having:
a raceway rollably supporting the at least one roller, and
a flange extending from an axial end of the raceway and including a flange surface that contacts the roller end surface, the flange surface comprising a spherical flange surface section with a second curvature and a first opening flange surface section with a third curvature that is less than second curvature,
wherein the first curvature differs from the second curvature such that a first gap (di) exists between the at least partially spherical roller end surface and the spherical flange surface section, and
a second gap (d2) exists between at least partially spherical roller end side and the first opening flange surface section, the second gap (d2) being larger than the first gap (d1).
1. A bearing ring for a roller bearing having a raceway for at least one roller that includes an at least partially spherically formed roller end surface having a first curvature, the bearing ring comprising:
a flange disposed on an end-side of the roller for transferring axial forces, the flange having a flange surface facing towards the roller end surface, a spherical flange surface section having a second curvature being defined on the flange surface,
wherein the first and the second curvature differ such that a first gap dimension (d1) exists between the spherically formed roller end surface and the spherical flange surface section, and
the flange surface also has an opening flange surface section having a third curvature, which is less than the second curvature, such that a second gap dimension (d2) exists between the roller end side and the opening flange surface section, the second gap dimension (d2) being larger than the first gap dimension (d1).
20. A method for manufacturing a bearing ring having a raceway for at least one roller, the roller having an at least partially spherical roller end surface with a first curvature, the method comprising:
providing a flange on an end of the raceway for transferring axial forces, such that the flange includes a flange surface configured to face towards the roller end surface,
wherein said flange providing step further comprises:
providing a spherical flange section with a second curvature on the flange surface, the second curvature differing from the first curvature such that a first gap dimension (d1) exists between the spherically formed roller end surface and the spherical flange surface section, and
providing an opening surface section having a third curvature on the flange surface such that the third curvature is less than the second curvature and a second gap dimension (d2) exists between the roller end surface and the opening flange surface section, the second gap dimension (d2) being larger than the first gap dimension (d1).
2. The bearing ring according to
3. The bearing ring according to
4. The bearing ring according to
5. The bearing ring according to
a first opening flange surface section extends from a corner region between the raceway and the flange surface,
the spherical flange surface section connects to the first opening flange surface section in the radial direction, and
on a region of the spherical flange surface section facing away from the first opening flange surface section, a second opening flange surface section of the spherical flange surface section extends out to a radial end of the flange.
6. The bearing ring according to
7. The bearing ring according to
8. The bearing ring according to
11. The roller bearing according to
12. The roller bearing according to
an angle (α) is defined between a first plane, which is tangential to an imaginary portion of the spherical flange surface section that extends towards the opening flange surface section, and a second plane, which is tangential to the opening flange surface section, and 0°<α≦30°.
13. The roller bearing according to
14. The roller bearing according to
15. The roller bearing according to
the first opening flange surface section directly borders a corner connecting the raceway and the flange,
the spherical flange surface section directly borders the first opening flange surface section in the radial direction, and
a second opening flange surface section is defined on the flange surface, directly borders the spherical flange surface section in the radial direction and extends to a radially outermost end of the flange.
16. The roller bearing according to
17. The roller bearing according to
18. The roller bearing according to
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This application is the U.S. national stage of International Application No. PCT/EP2011/071157 filed on Nov. 28, 2011, which claims priority to German patent application no. 10 2010 062 481.0 filed on Dec. 6, 2010.
The present invention relates to a geometric concept for a roller-flange contact in roller bearings, in particular for a tapered-roller-flange-contact in tapered roller bearings.
Guide flanges in roller bearings, such as e.g. tapered roller bearings, can be embodied either straight or spherical. Straight flanges are mainly used for roller bearings of small diameter and thus also of smaller flange widths. In this case, a flange width is often too small to produce a defined profile on an available flange surface. Spherical flanges find application mostly in roller bearings having larger diameters and thus also having larger flange widths. A spherical flange is characterized in that a radius, which describes a flange shape facing towards a roller raceway, has its origin substantially on an axis of rotation of the rollers (roller rotational axis), wherein small deviations are allowed due to alignment errors.
For a more detailed description of roller bearings having spherical flanges,
The tapered rollers 13 can roll on an inner raceway 14, which is formed in the bearing inner ring 11, and on an outer raceway 15, which is formed in the bearing outer ring 12. Considering a tapered roller bearing in three-dimensions, the raceways 14, 15 are formed as conical outer surfaces. In the longitudinal section shown in
During an operation of the bearing 10, each (tapered) roller 13 rotates around its own roller axis 20, wherein an imaginary extension of the roller axis 20 also intersects with the pivot point 19. A rolling condition on the raceways 14, 15 for the tapered rollers 13 is realized by a relative position of inner line 16, outer line 17, bearing axis of rotation 18, and roller axis 20, which all intersect in the pivot point 19, so that with a relative rotation of bearing inner ring 11 and bearing outer ring 12, the tapered rollers 13 roll on the raceways 14, 15 substantially without slippage, and an amount of friction related thereto is minimized.
When supporting axial forces, in order to also optimize the friction that occurs in the axial direction i.e. in the direction of the bearing rotational axis 18, the rollers 13 used in roller bearings can have a first curvature, on their end side 21, identified by a first radius R21, so that a part of a ball surface results as an end side surface of the rollers 13, which, as is indicated in the enlargement of
In roller bearings, such as for example cylindrical roller, barrel roller, or ball bearings, which are designed with straight or flat flanges, in comparison to spherically embodied flanges the roller-flange contact has a higher surface pressure (Hertzian pressure) between the roller end side 21 and the flange surface facing towards this. Here the Hertzian pressure is understood to be the greatest pressure that prevails in the middle of the contact surface of two elastic bodies. If, such as with roller bearings with straight flanges, two elastic bodies (curved roller end side and straight or flat flange) are pressed against each other, then in the ideal case they touch only in a punctiform manner. However, in the real case, a flattening and thus a contact surface arises at the contact point 22 due to the elasticity. A characteristic pressure distribution (surface pressure) arises on the contact surface in both bodies, wherein the pressure is always highest in the middle. If, as here, a ball outer surface and a flat flange surface touch, a touch- or contact-ellipse results. Due to the comparatively high surface pressure, with roller bearings having straight flanges, a relatively poor lubricant film formation generally results at higher effective forces. In addition, in comparison to spherical flanges, straight or flat flanges lead to smaller contact ellipses between the roller end side and the flange surface facing this, for which reason an overlapping of the contact ellipse with the flange edges can result only with extreme loads. Likewise, with straight- or flat-embodied flanges, there is a low sensitivity of the contact point 22 to alignment errors, so that a defined contact point 22 between roller 13 and flange is possible. While on the one hand a greater skewing of the roller 13 is made possible with flat-embodied flanges, on the other hand a relatively poor guiding of the rollers results during operation.
Tapered roller bearings in the large bearing field can, as shown with reference to
However, one of the main disadvantages of a spherical flange is the resulting sensitivity of the contact point 22 between the roller end side 21 and the flange 23 to alignment error. Deviations in the raceway angle, roller angle, flange radius, as well as roller end side radius have a decisive influence thereon.
Therefore, in one aspect of the present teachings, techniques are disclosed to reduce this sensitivity of the contact point between the roller end side and the flange to alignment error.
In order to reduce the sensitivity of the roller-flange contact point to alignment error, but nevertheless to be able to ensure a sufficient guiding of the roller during operation, an appropriately optimized flange surface geometry is proposed herein. For this the proposed flange surface geometry has on the one hand a spherical section which should ensure the roller guiding as well as a low Hertzian pressure. On the other hand, the proposed flange geometry also has what is referred to below as an opening section, which produces a larger gap dimension, i.e. a larger spacing, between the roller end surface and the flange surface facing towards this, than would be provided with a purely spherically formed flange.
For this, exemplary embodiments of the present invention provide a bearing ring for a roller bearing having a raceway for at least one roller, which has an at least partially spherically formed roller end surface having a first curvature. For transferring axial forces, the bearing ring has a flange disposed on an end-side of the roller, which flange has a flange surface facing towards the roller end side, wherein the flange surface comprises a spherical flange surface section having a second curvature, which can be designed as constant or variable on the spherical flange surface section. The first and the second curvature are chosen so as to achieve a first gap dimension (which depending on the roller-flange geometry can also be a mean gap dimension) between the spherically-designed roller end surface and the spherical flange surface section. In addition, the flange surface has an opening flange surface section having a lesser-than-the-second curvature for a larger-than-the-first gap dimension between the roller end surface and the opening flange surface section.
According to a further aspect, a method is also provided for manufacturing a bearing ring for a roller bearing having a roller raceway for at least one roller, wherein the roller has a spherically-designed roller end surface having a first curvature. The method comprises a step for providing a flange disposed on an end-side of the roller for transferring axial forces, which flange has a flange surface facing towards the roller end surface, wherein the provision step in turn includes the following steps:
According to exemplary embodiments, the second curvature of the spherical flange surface section can be designed as constant or variable.
According to exemplary embodiments, a first tangential plane to a hypothetical purely spherically extending flange surface, instead of the opening surface section in this region, and a second tangential plane to the opening flange surface section enclose a maximum angle α, which is larger than 0° and smaller than or equal to 30°.
According to exemplary embodiments, the spherical flange surface section extends over an area of at least one third of the flange surface.
According to some exemplary embodiments, the spherical flange surface section extends from a corner region between the raceway and the flange surface to a radial end of the flange or a flange edge. In a bearing inner ring, the spherical flange surface section can thus lie in a lower region of the flange, which lower region faces towards an inner race and adjacent to a flange or groove edge, wherein the opening flange section in this case, bordering the spherical flange surface section, lies in the upper region of the flange. In a bearing outer ring it is correspondingly reversed, i.e. the spherical flange section here lies in an upper region of the flange bordering a flange or groove edge, wherein the opening flange section is then located in the lower region of the flange, which lower region faces way from the outer race.
However, according to other exemplary embodiments it is also possible that the spherically-designed section does not border the flange edge between raceway and flange, so that opening flange surface regions are located above and below the spherical section. In this case, a first opening flange surface section extends from a corner region between the raceway and the flange surface, wherein the spherical flange surface section connects to the first opening flange surface section in the radial direction. On a region of the spherical flange surface section facing away from the first opening flange surface section, a second opening surface section extends in the radial direction from the spherical flange surface section to a radial end of the flange.
According to exemplary embodiments the roller bearing is a tapered roller bearing. The roller is then accordingly formed as a tapered roller.
Due to the proposed roller-flange contact geometry in the form of a spherical flange surface section in combination with a directly-bordering opening flange surface section, the roller guiding during operation can be preserved due to the spherically formed flange section. The spherical flange surface section additionally provides for a low Hertzian pressure.
The opening flange section can reduce a size of the contact ellipse in comparison to purely spherical flanges, whereby an overlapping of the contact ellipse with the flange edges can be avoided. Due to the opening flange regions, there is also a lower sensitivity of the location of the contact point between roller end side and flange to alignment errors, so that a defined contact point between roller and flange is made possible.
The proposed roller-flange geometry is designed such that in the ideal geometry the contact point or region between roller end side and flange lies in the spherical flange region.
The sensitivity of the contact point to alignment errors is comparable in the spherical flange region to the sensitivity of a purely spherical flange. However, the contact point shifts due to deviations in shape in the opening flange region; thus the sensitivity is greatly reduced, which can prevent a “wandering” of the theoretical contact point out over the flange edges and thus also can prevent the above-mentioned high edge stresses.
Exemplary embodiments of the present invention are explained in more detail below with reference to the accompanying figures:
A part of a bearing ring 30 is depicted for the roller bearing having a raceway 14 for at least one roller 13. The roller 13 has a curved roller end surface 21 having a first curvature, which curved roller end surface 21 can be formed e.g. partially spherical. The bearing ring 30 has a flange 31 for transferring axial forces, which flange 31 is disposed end-side to or on the end side of the roller 13 having a flange surface 32 facing towards the roller end surface.
As depicted in the enlarged view of
In this case curvature shall be understood to mean a change of direction per unit length. The curvature e.g. of a straight line is everywhere equal to zero, since its direction does not change. A circle having a radius r has the same curvature everywhere (namely 1/r), since its direction changes everywhere equally strongly. With all other curves the curvature changes from curve point to curve point. The curvature of a curve at a point thus indicates how strongly the curve deviates, in the immediate vicinity of the point, from a straight line. In a curved surface, such as for example the flange surface 32, one notices its curvature for example in a quadratically increasing deviation of the surface from its tangential plane. A stronger curvature makes itself noticeable as a stronger deviation from the plane. For the present case this also means, for example, that the spherical flange surface section 33 deviates more strongly per path length from a tangential plane to the opening flange surface section 34 of the flange surface 32 than regions of the opening flange surface section 34 itself.
The spherical roller end surface 21 is described by a first radius R21, which can have its origin substantially on the axis of rotation 20 of the roller 13. The spherical flange surface section 33 is described by a second radius R33, which is larger than the first radius R21 (i.e. R21<R33) and which can have its origin substantially on the axis of rotation 18 of the roller bearing 10. The radii R21 and R33 or the surfaces 21 and 33 described thereby can indeed be in principle disposed concentric, i.e. with an identical origin on the roller rotational axis 20. In order to at least theoretically obtain a defined contact point 22 between the roller end surface 21 and the spherical flange surface section 33, the radii R21 and R33 or the surfaces 21 and 33 described thereby can generally speaking (as here) also be disposed non-concentric, i.e. with a non-identical origin on the roller rotational axis 20 or bearing rotational axis 18. In any case, the first R21 and the second radius R33 and their origins are chosen so as to achieve a first gap dimension d1 between the spherically-designed roller end surface 21 and the spherical flange surface section 33, which first gap dimension d1 can assume a maximum value d1,max. However, the opening flange surface section 34 now has according to the invention, a lesser curvature than the spherical flange surface section 33, so that between the opening flange surface section 34 and the spherical roller end surface 21a second gap dimension d2 arises, which, starting from the maximum value d1,max out to a radial end of the opening flange surface section 34 or out to one of the flange edges 36 facing away from the raceway 14 increases up to a maximum value d2,max, i.e. d1,maxd≦d2≦d2,max.
In the exemplary embodiment illustrated in
As is shown in
According to exemplary embodiments, the opening flange surface section 34 makes possible an opening of the flange 31 or of the flange surface 32 relative the spherical flange surface section 33 in an angular range α from greater than 0° to 30°, preferably in a range 0° 0′ 6″≦α≦30°. The opening angle α of the opening flange surface 34 relative to the spherical flange surface section 33 can be obtained, for example, by determining the largest angle between a tangential plane 38 to the spherical flange surface section that is hypothetically extended into the opening flange surface section and a tangential plane 39 to the opening flange surface segment 34. For this, the largest angle between a group of tangential planes 38 to the spherical flange surface section that is hypothetically extended into the opening flange surface section, and a group of tangential planes 39 to the opening flange surface section 34 can be determined. The spherical flange surface section that is hypothetically extended into the opening flange surface section is indicated in
According to exemplary embodiments of the present invention, the spherical flange surface section 33 extends over a flange surface section corresponding to at least one third of a flange height h of the flange 31. That is, a height h33 of the spherical flange surface section 33 corresponds to at least one third of the entire flange height h, i.e. h33≧⅓h. Accordingly, a height h34 of the opening flange surface section 34 directly adjacent thereto is at most two thirds of the total flange height h, i.e. h34≦⅔h. Preferably a height h33 of the spherical flange surface section 33 falls within a range of ⅓h≦h33≦¾h and accordingly the height h34 of the opening flange surface section 34 falls within a range ¼h≦h34≦⅔h.
There are different possibilities for the embodiment of the opening flange region 34. Although
After exemplary embodiments have been described with reference to
According to the exemplary embodiment illustrated in
According to
In all exemplary embodiments, the roller-flange contact geometry is chosen such that the contact point 22 lies in the region of the spherical flange surface section 33. The opening regions 34, which can also be formed spherical, however with lesser curvature than the spherical region 33, or can be flat or straight, respectively make possible an opening a of the flange 31 that guides the roller 13, of approximately 0° 0′ 6″ to 30° in comparison to a flange geometry with a completely spherically-designed flange.
For the sake of completeness, a manufacturing method 60 for manufacturing a bearing ring for a roller bearing having a raceway for at least one roller 13 will now be explained with reference to
The manufacturing process 60 includes a step 61 for preparing a flange 31 disposed on an end side of the roller for transferring axial forces, which flange 31 has a flange surface 32 facing towards the roller end surface 21.
The step 61 can in turn be subdivided in a first substep 611 for preparing/producing a spherical surface section 33 of the flange surface 32 having a second curvature, wherein the second curvature is chosen with respect to the first curvature so as to achieve a first gap dimension d1 between the spherically-formed roller end surface 21 and the spherical flange surface section 33.
According to a second substep 612, an opening surface section 34 of the flange surface 32 is also provided or produced, which opening surface section 34 has a lesser-than-the-second curvature for an enlarged gap dimension d2, with respect to the first gap dimension d1, between the roller end surface 21 and the opening flange surface section 34. It has already been discussed in detail in the foregoing.
In summary, the proposed flange shape is thus to be sought, in order to reduce the sensitivity of the roller-flange contact point 22 to alignment errors and skewing of the bearing in use, but nevertheless to be able to ensure a sufficient guiding of the roller 13 on the raceway during operation. The inventive flange geometry has a spherical section 33, which can ensure the roller guiding as well as a low Hertzian pressure. Furthermore, the proposed flange geometry has at least one opening section 34, which produces a larger gap dimension between the roller end surface 21 and the flange surface 32 than would be provided by a purely spherical flange.
The spherical section 33 can for example be used in the lower region of the flange 31 (bordering the flange edge/groove edge), wherein in this case the opening flange section 34 lies in the upper region of the flange (see
The inventive roller-flange-contact-geometry of a spherical flange in combination with an opening section has the following advantageous features:
The proposed roller-flange geometry is designed such that in the ideal geometry, the roller end side and the flange lie in the spherical flange region. The sensitivity of the contact point to alignment errors is identical in the spherical flange section to the sensitivity of a purely spherical flange. If the contact point shifts due to alignment errors in the opening flange section, then the sensitivity is greatly reduced, which can prevent a “wandering” of the theoretical contact point out over the flange edge and thus can also prevent high edge pressures.
There are different possibilities for the embodiment of the opening flange section. For one, a straight flange region would be conceivable, which connects tangentially to the arc of the spherical flange region. The opening flange region could also be defined by a radius which is larger than the radius of the spherical region.
Although the present invention has been described with reference to an embodiment having tapered roller bearings and tapered rollers, exemplary embodiments are not limited to such designs. In principle, the present invention can also be applied to other rollers and roller bearings, such as e.g. to cylindrical and barrel roller bearings.
Reugels, Michael, Liang, Baozhu
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Jul 05 2013 | LIANG, BAOZHU | Aktiebolaget SKF | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 031020 | /0378 | |
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